References about this question : t-test for single sample (a.k.a. one-sample t-test) ; t-test for dependent means (a.k.a. repeated-measures t-test) ; t-test for independent means

Question: An industrial researcher is a consultant to a large chain of bookstores. Industry reports show that for book stores in general, the average number of complaints received by management for a 1-month period at this time of year is 6.5 (the variance is not known). Seven of this chain's stores are randomly selected to keep records of complaints received over a 1-month period. The numbers of complaints are 4, 8, 9, 0, 3, 5, and 6. Does this chain get a different amount of complaints than bookstores in general? (Use the .05 level).

What is the value for the degrees of freedom?

In the question above, What is the estimated population variance? (please round off to 2 decimal places)

In the question above, What is the standard deviation on the distribution of means? (please round off to two decimal places)

In the question above, What is the cutoff score on the t distribution?(please use the t table; do not round off)

In the question above, what is the t value? (round off to 2 decimal places)